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CSC 1040 – Algorithms and Data Structures I

CSC 1040 – Algorithms and Data Structures I. Introduction to Computing with Images. Dr. Mary-Angela Papalaskari Department of Computing Sciences Villanova University Course website: www.csc.villanova.edu/~map/1040/

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CSC 1040 – Algorithms and Data Structures I

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  1. CSC 1040 – Algorithms and Data Structures I Introduction to Computing with Images Dr. Mary-Angela Papalaskari Department of Computing Sciences Villanova University Course website: www.csc.villanova.edu/~map/1040/ Some slides in this presentation are adapted from the slides accompanying Java Software Solutions by Lewis & Loftus CSC 1040 M.A. Papalaskari, Villanova University

  2. What is this course about? • Computer Science • Problem solving • Algorithmic thinking • Data representation • Images and graphics • Visual communication CSC 1040 M.A. Papalaskari, Villanova University

  3. Our textbook An Interdisciplinary Introduction to Image Processing Pixels, Numbers, and Programs Steven L. Tanimoto The MIT Press

  4. Reverse History of computing Examine what we already know, travel backwards… • What we see now all around us – a connected world of computing • Focus on a single “traditional” computer • Dig deeper – data and processing CSC 1051 M.A. Papalaskari, Villanova University

  5. Networks A network is two or more computers that are connected so that data and resources can be shared A Local-Area Network (LAN) covers a small distance and a small number of computers A Wide-Area Network (WAN) connects two or more LANs, often over long distances CSC 1051 M.A. Papalaskari, Villanova University

  6. The Internet • History: Started as a United States government project, sponsored by the Advanced Research Projects Agency (ARPA) in late 1970’s • 1980’s: ARPANET • the wide area network and Protocols for communication, including url’s developed • 1990’s: World Wide Web • html and web browsers CSC 1051 M.A. Papalaskari, Villanova University

  7. IP and Internet Addresses • Each computer on the Internet has a unique IP address, such as: 204.192.116.2 • Most computers also have a unique Internet name, which also is referred to as an Internet address: hector.vt.edu kant.gestalt-llc.com • The first part indicates a particular computer (hector) • The rest is the domain name, indicating the organization (vt.edu) CSC 1051 M.A. Papalaskari, Villanova University

  8. Domain Names • The last part of a domain name, called a top-level domain (TLD), supposedly indicates the type of organization: edu educational institution com commercial entity org non-profit organization net network-based organization Sometimes the suffix indicates the country: uk United Kingdom au Australia ca Canada se Sweden Additional TLDs have been added: biz, info, tv, name CSC 1051 M.A. Papalaskari, Villanova University

  9. The World Wide Web • The World Wide Web allows many different types of information to be accessed using a common interface • A browser is a program which accesses network resources and presents them • Popular browsers: Internet Explorer, Safari, Firefox • Resources presented include: • text, graphics, video, sound, audio, executable programs • A Web document usually contains links to other Web documents, creating a hypermedia environment • The term Web comes from the fact that information is not organized in a linear fashion CSC 1051 M.A. Papalaskari, Villanova University

  10. The World Wide Web • Web documents are often defined using the HyperText Markup Language (HTML) • Information on the Web is found using a Uniform Resource Locator (URL): http://www.cnn.com http://www.vt.edu/student_life/index.html ftp://java.sun.com/applets/animation.zip • A URL specifies a protocol (http), a domain, and possibly specific documents CSC 1051 M.A. Papalaskari, Villanova University

  11. Reverse History of computing Examine what we already know, travel backwards… • What we see now all around us – a connected world of computing • Focus on a single “traditional” computer • Dig deeper – data and processing CSC 1051 M.A. Papalaskari, Villanova University

  12. A Computer Specification • Consider the following specification for a personal computer: • 3.07 GHz Intel Core i7 processor • 4 GB RAM • 750 GB Hard Disk • 16x Blu-ray / HD DVD-ROM & 16x DVD+R DVD Burner • 17” Flat Screen Video Display with 1280 x 1024 resolution • Network Card CSC 1051 M.A. Papalaskari, Villanova University

  13. Computer Architecture CSC 1051 M.A. Papalaskari, Villanova University

  14. 9278 9279 9280 9281 9282 9283 9284 9285 9286 Main memory is divided into many memory locations (or cells) Each memory cell has a numeric address, which uniquely identifies it Memory CSC 1051 M.A. Papalaskari, Villanova University

  15. Why is main memory called “RAM”???? CSC 1051 M.A. Papalaskari, Villanova University

  16. “Random Access Memory (RAM)” 9278 9279 9280 9281 9282 9283 9284 9285 9286 You don’t have to scan the memory sequentially – go to data directly using the address 10011010 CSC 1051 M.A. Papalaskari, Villanova University

  17. Memory characteristics • Direct accessor Random access – information can be reached directly (as opposed to sequentially as in the case of magnetic tape) • Volatile - stored information is lost if the electric power is removed • Read/Write – information can be overwritten (as opposed to read-only devices – ROM) CSC 1051 M.A. Papalaskari, Villanova University

  18. What is “ROM”?is it the opposite of “RAM”???? CSC 1051 M.A. Papalaskari, Villanova University

  19. What is “ROM”?is it the opposite of “RAM”???? Read Only Memory CSC 1051 M.A. Papalaskari, Villanova University

  20. What is “ROM”?is it the opposite of “RAM”???? Read Only Memory NO! ROM is also random access CSC 1051 M.A. Papalaskari, Villanova University

  21. RAM vs. ROM • RAM - Random Access Memory • synonymous with main memory: • fast • read/write • volatile • random access • ROM - Read-Only Memory • ROM typically holds the firmware, eg BIOS • fast (except in CD-ROM) • read only • non-volatile • random access CSC 1051 M.A. Papalaskari, Villanova University

  22. Random Access Memory Devices CSC 1051 M.A. Papalaskari, Villanova University

  23. Random Access Memory Devices Electronic circuits CSC 1051 M.A. Papalaskari, Villanova University

  24. Random Access Memory Devices magnetic CSC 1051 M.A. Papalaskari, Villanova University

  25. Random Access Memory Devices optical CSC 1051 M.A. Papalaskari, Villanova University

  26. Storage Capacity • Every memory device has a storage capacity, indicating the number of bytes it can hold • Capacities are expressed in various units: CSC 1051 M.A. Papalaskari, Villanova University

  27. CPU and Main Memory Chip that executes program commands Central Processing Unit Primary storage area for programs and data that are in active use Synonymous with RAM Main Memory CSC 1051 M.A. Papalaskari, Villanova University

  28. CPU and Main Memory Historic note: Von Neuman architecture John Von Neuman, USA 1945 Chip that executes program commands Central Processing Unit Primary storage area for programs and data that are in active use Synonymous with RAM Main Memory CSC 1051 M.A. Papalaskari, Villanova University

  29. Retrieve an instruction from main memory fetch execute decode Carry out the instruction Determine what the instruction is The Central Processing Unit • A CPU is on a chip called a microprocessor • It continuously follows the fetch-decode-execute cycle: CSC 1051 M.A. Papalaskari, Villanova University

  30. Retrieve an instruction from main memory fetch execute decode Carry out the instruction Determine what the instruction is The Central Processing Unit • A CPU is on a chip called a microprocessor • It continuously follows the fetch-decode-execute cycle: system clock controls speed, measured in gigahertz (GHz) CSC 1051 M.A. Papalaskari, Villanova University

  31. The Central Processing Unit Performs calculations and makes decisions Arithmetic / Logic Unit Coordinates processing (system clock, decoding, etc) Control Unit Registers Small, very fast memory CSC 1051 M.A. Papalaskari, Villanova University

  32. Historic Note: Automatic control of computation • The concept of a machine that can follow a series of steps - a “program” • Some early steps: • Jacquard loom (1801) • Babbage's Difference engine and Analytical engine (1822) • Holerith's census machine (1890) • Stored program and the fetch/decode/execute cycle (John von Neumann, 1945) • ENIAC - first fully electronic digital computer (Eckert and Mauchley, 1946) CSC 1051 M.A. Papalaskari, Villanova University

  33. Reverse History of computing Examine what we already know, travel backwards… • What we see now all around us – a connected world of computing • Focus on a single “traditional” computer • Dig deeper – data and processing CSC 1051 M.A. Papalaskari, Villanova University

  34. Data Representation • Computers store all information digitally, using binary codes: • numbers • text • images • audio • video • program instructions CSC 1051 M.A. Papalaskari, Villanova University

  35. Analog vs. Digital Data • Analog • continuous, in direct proportion to the data represented • music on a record album - a needle rides on ridges in the grooves that are directly proportional to the voltages sent to the speaker • Digital • information is broken down into pieces, and each piece is represented separately • sampling – record discrete values of the analog representation CSC 1051 M.A. Papalaskari, Villanova University

  36. Binary Numbers • Number system consisting of 1’s & 0’s • Simplest way to represent digital information • modern computers use binary numbers internally A binary digit is called abit - binary digit A byte is a group of eight bits CSC 1051 M.A. Papalaskari, Villanova University

  37. Representing and processing bits • Electronic circuits: high/low voltage • Magnetic devices (eg hard drive): positive/negative • Optical devices (eg DVD): light reflected/not reflected due to microscopic grooves CSC 1051 M.A. Papalaskari, Villanova University

  38. 1 bit 2 bits 3 bits 4 bits 0 1 00 01 10 11 000 001 010 011 100 101 110 111 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Bit Permutations Each additional bit doubles the number of possible permutations CSC 1051 M.A. Papalaskari, Villanova University

  39. 1 bit ? 2 bits ? 3 bits ? 4 bits ? 5 bits ? How many items can be represented by Bit Permutations • How many permutations of N bits? • How many bits are needed to represent 64 items? • How many bits are needed to represent 100 items? CSC 1051 M.A. Papalaskari, Villanova University

  40. Binary Representation of Information • Computers store all information digitally, using binary codes: • numbers • text • images • audio • video • program instructions CSC 1051 M.A. Papalaskari, Villanova University

  41. Representing Text Digitally • For example, every character is stored as a number, including spaces, digits, and punctuation • Corresponding upper and lower case letters are separate characters H i , H e a t h e r . 72 105 44 32 72 101 97 116 104 101 114 46 ASCII / UNICODE 01100001 binary CSC 1051 M.A. Papalaskari, Villanova University

  42. Representing Images • RGB Color • 3 colors: red, green, blue • 8 bits/color • 24 bits • Bitmap • 1 bit • Grayscale • 8 bits CSC 1051 M.A. Papalaskari, Villanova University

  43. red=108 green=86 blue=142 y = 9 Color:(108,86,142) Position: (12,9) x = 12 CSC 1051 M.A. Papalaskari, Villanova University

  44. E.g., could be the code that causes input of a symbol from the keyboard Program instructions are also encoded in binary 9278 9279 9280 9281 9282 9283 9284 9285 9286 10011010 CSC 1051 M.A. Papalaskari, Villanova University

  45. a number? a letter? the red component of a pixel? a program instruction? Memory devices store data of all kinds 9278 9279 9280 9281 9282 9283 9284 9285 9286 10011010 CSC 1051 M.A. Papalaskari, Villanova University

  46. Each memory cell stores a set number of bits (usually 8 bits, or one byte) Large values are stored in consecutive memory locations Memory devices store data of all kinds 9278 9279 9280 9281 9282 9283 9284 9285 9286 10011010 CSC 1051 M.A. Papalaskari, Villanova University

  47. Historic note: Great human developments that gave rise to the modern computer • Mechanization of arithmetic – the concepts of numbers, symbols, algorithms, and computation • Automatic control of computation – a “program” to control operations (fetch/decode/execute cycle and the stored program concept) CSC 1051 M.A. Papalaskari, Villanova University

  48. Historic Note: Mechanization of arithmetic • Development of number systems • Abacus (2400 BC) • Number systems (Babylonian, Greek, Roman, Arabic 1000 BC - 800 AD) • The notion of an algorithm • Euclid (300 BC) • al-Khwārizmī (780 AD) • Creation of special purpose calculators • Stonehenge (1900-1600 BC) • Napier's bones (1600, a precursor of the slide rule) • Pascal's adder (1642) • Leibniz's calculator (1670s) • modern calculators CSC 1051 M.A. Papalaskari, Villanova University

  49. Mechanization of Arithmetic + Automatic Control of Computation = Modern Computer CSC 1051 M.A. Papalaskari, Villanova University

  50. Computer Science Can be viewed as a culmination of humanity’s search for understanding of: • Problem solving • Mechanization • Computation • Representation & encoding • Abstraction Just like Physics and other sciences branched off from philosophy during the renaissance, so CS emerged in the 20th century from the work of philosophers and mathematicians (with the help of dedicated, visionary practitioners, experimental scientists and engineers). CSC 1051 M.A. Papalaskari, Villanova University

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